Solvent & diluent refer to the chemical substances that can reduce the viscosity of resin system, make resin and other components mix better, or make adhesive better applied to the surface of substrate.
Compared with polymer, solvent diluent are small components, which are compatible with resin and curing agent in chemical and physical aspects.
The difference between solvents and diluents is the vapor pressure. Another view is that the solvent can dissolve the main resin and additives, while the role of diluent is mainly to reduce the viscosity of the paint system.
The vapor pressure of the solvent is relatively high, and it will evaporate under certain environmental conditions. Some solvents can volatilize rapidly at room temperature and atmospheric pressure, while others may need to volatilize at high temperature and under atmospheric pressure.
The vapor pressure of diluent is very low, and it will not volatilize at normal temperature. The main function of diluent in the formulation system is to reduce viscosity, improve the mixing of resin and filler, increase the amount of filler, or improve the application performance.